Analytical development and optimization of a graphene-solution interface capacitance model

Graphene, which as a new carbon material shows great potential for a range of applications because of its exceptional electronic and mechanical properties, becomes a matter of attention in these years. The use of graphene in nanoscale devices plays an important role in achieving more accurate and faster devices. Although there are lots of experimental studies in this area, there is a lack of analytical models. Quantum capacitance as one of the important properties of field effect transistors (FETs) is in our focus. The quantum capacitance of electrolyte-gated transistors (EGFETs) along with a relevant equivalent circuit is suggested in terms of Fermi velocity, carrier density, and fundamental physical quantities. The analytical model is compared with the experimental data and the mean absolute percentage error (MAPE) is calculated to be 11.82. In order to decrease the error, a new function of E composed of α and β parameters is suggested. In another attempt, the ant colony optimization (ACO) algorithm is implemented for optimization and development of an analytical model to obtain a more accurate capacitance model. To further confirm this viewpoint, based on the given results, the accuracy of the optimized model is more than 97% which is in an acceptable range of accurac

Improving waveform quality in direct power control of DFIG using fuzzy controller

This paper proposes a new direct power control (DPC) strategy of double-fed induction generator using fuzzy logic controller. The active and reactive power equations are expanded, and effects of voltage vectors on active and reactive power variations are investigated quantitatively. The selection of the voltage vectors is performed using fuzzy system which is used instead of optimal switching table. Four variables are used as inputs of the fuzzy system which are errors of active and reactive powers, real time value of the rotor speed and stator flux position. The defuzzified output is the optimal selected voltage vector. MATLAB/Simulink software is used for the purpose of simulation and the results reported show the effectiveness of the proposed method in improving the waveform quality. Compared with the conventional DPC, the proposed fuzzy technique can reduce the power out of band percentage by about 25 % which is very impressiv